Nighttime legibility of traffic signs: conditions eliminating the effects of driver age and disability glare

The effects of observer age and environmental glare on nighttime legibility of traffic signs were investigated in two field experiments with the subjects driving or riding in a car towards a sign. Experiment 1 showed that equating older and younger subjects in terms of their low luminance/high contrast visual acuity resulted in elimination of any age effects on legibility. Furthermore, the presence of a glare source with an illuminance of 0.17 or 0.017 lux offset 2° from the sign legend improved legibility distance significantly. The results of Experiment 2 indicated that a glare source with an illuminance of 0.0098 lux had no effect on legibility when presented at an offset angle of 1.5° or 0.6°, but it had a significant detrimental effect at an offset angle of 0.2°. The present findings suggest that (1) the usually observed age-related performance decrement on nighttime legibility tasks is the result of visual-acuity deficits, and not shortcomings in information-processing ability; (2) legibility is relatively unaffected by glare, unless the glare angle is very small or glare level very high; and (3) glare sources positioned outside of the fovea might improve nighttime legibility performance under certain conditions.     

Mapping of the Saccharomyces cerevisiae CDC3, CDC25, and CDC42 genes to chromosome XII by chromosome blotting and tetrad analysis

CDC3, CDC25 and CDC42 were localized to chromosome XII by hybridizing the cloned genes to Southern blots of chromosomes separated by orthogonal-field-alternation gel electrophoresis. Meiotic tetrad analyses further localized these genes to the region distal to the RDN1 locus on the right arm of the chromosome. The STE11 gene, which had previously been mapped to chromosome XII (Chaleff and Tatchell, 1985), was found to be tightly linked to ILV5. The data suggest a map order of CEN12-RDN1-CDC42-(CDC25-CDC3)-(ILV5- STE11)-URA4. Certain oddities of the data set raise the possibility that there may be constraints on the patterns of recombination in this region of chromosome XII.     

Nonlinear transient response of stiffened plates to air blast loading by a superelement approach

In this paper, new plate and stiffener beam elements are developed for the nonlinear dynamic analysis of stiffened plate structures subject to blast-type pressure waves. The displacement fields for the elements are represented by polynomial and analytical functions in both in-plane directions and they have been constructed so that only one element per bay or span is required to model the response. Geometric and material nonlinearities are included and the temporal equations are solved by the implicit Newmark beta method with Newton-Raphson sub-iteration. The new formulation has been tested on several numerical examples and the results obtained are compared with other available solutions. The present model is simple, requires much reduced storage and computing time and yet gives results suitable for practical design purposes.     

A neural network approach to job-shop scheduling

A novel analog computational network is presented for solving NP-complete constraint satisfaction problems, i.e. job-shop scheduling. In contrast to most neural approaches to combinatorial optimization based on quadratic energy cost function, the authors propose to use linear cost functions. As a result, the network complexity (number of neurons and the number of resistive interconnections) grows only linearly with problem size, and large-scale implementations become possible. The proposed approach is related to the linear programming network described by D.W. Tank and J.J. Hopfield (1985), which also uses a linear cost function for a simple optimization problem. It is shown how to map a difficult constraint-satisfaction problem onto a simple neural net in which the number of neural processors equals the number of subjobs (operations) and the number of interconnections grows linearly with the total number of operations. Simulations show that the authors' approach produces better solutions than existing neural approaches to job-shop scheduling, i.e. the traveling salesman problem-type Hopfield approach and integer linear programming approach of J.P.S. Foo and Y. Takefuji (1988), in terms of the quality of the solution and the network complexity.     

A magnetic head for 150 MHz, high density recording

A multilayered magnetic head that can read and write at 150 MHz on metal particle tape with a coercivity of 120 kA/m (1500 Oe) has been developed. Ten 2-μm layers of Fe₆₈Ru₈Ga₇ Si₁₇ alloy, with 100 nm of SiO₂ used as spacer, form the magnetic-core thickness and the track width. The head was tested in a rotary recording system at a relative head-to-tape speed of 73 m/s. At a linear density of 4000 fc/mm (100 kfc) and 150 MHz, the measured single frequency signal to 300-kHz-slot noise was 33 dB (RMS-RMS). The measured frequency response curve agrees with theory and indicates a head-to-tape spacing of 70 nm at high speed. The read efficiency of the head decreases from 37% at low frequency to 15% at 150 MHz     

Oxidation-reduction reactions of CeMO4+x (M = Ta or Nb) phases

Phase equilibrium methods, single crystal and powder x-ray diffraction analyses, thermogravimetric analysis and magnetic susceptibility measurements were utilized to define subsolidus phase relations $\text{in air}$ for the systems cerium oxide - Ta₂O₅ and cerium oxide - Nb₂O₅. Stoichiometric CeTaO₄ is stable in air (P_O2 = 0.21 atm) only above 1265°C. At 1265°C, the reversible reaction, $\text{3}\text{CeTaO}{}_4\text{+}\text{1}\text{2}\text{?}$CeTa₃O₉ + 2CeO₂ is established. If CeTaO₄ is quenched to room temperature and $\text{reheated}$ below 1000°C, or, if the material is rapidly cooled from above 1265°C to below 1000°C it absorbs oxygen according to, . The x parameter is variable and temperature dependent. Using a thermal microbalance, three distinct complex reaction series involving a homogeneity range in x were established, (a) 0.50 ≥ × ≥ 0.48 (<350°–600°C), (b) 0.17 ≥ × ≥ 0.06 (600°–950°C), (c) 0.40 ≥ × ≥ 0.34 (950°-room temperature). CeNbO₄ (not isostructural with CeTaO₄) also absorbs oxygen below ≈700°C in air to yield CeNbO_4+x materials.     

The aging effect of the thermoelectric power of thin copper films

The thermoelectricpower, referenced to bulk copper, of thin films of copper about 150 Å thick was measured by preparing a thin film bridge between two copper wires which served as leads. This arrangement produces two junctions between the thin film copper and the bulk copper. The two junctions were maintained at a temperature difference which was measured using a calibrated copper-constantan thermocouple. It was found that the thin film-to-bulk thermoelectric power varies with time and can be fitted to an equation of the form

$\text{S = S}{}_{\mathrm{<mtext>F</mtext>}}\text{(1?}\text{e}{}^{\mathrm{-\lambda t}}\text{)}$

where λ depends on temperature. The constant λ in the equation has values very close to those found from thin film resistance aging measurements, suggesting that the same mechanism is responsible for both aging phenomena. The heated junctions is negative, in agreement with a simple electron diffusion model of thermoelectric power.     

Clinical and prognostic aspects of adrenocortical neoplasms in childhood

BACKGROUND: A retrospective study of 54 children was undertaken to define the clinical presentation and secretory patterns of adrenal tumors and to evaluate the outcome of surgical resection and medical therapy. PROCEDURES: Different factors were studied in univariate and multivariate analysis by using the Cox proportional hazard model. RESULTS: Median age at diagnosis was 4 years. Boys and girls were affected equally. The disease was revealed by virilization (61%) or by a palpable mass (39%) with a 0.1-5.5 year delay from initial symptoms. At initial examination, we found that 76% of children were virilized. Ninety-four percent of the tested tumors secreted androgens, which were associated with glucocorticoids in 36%. Adrenal tumors in children were smaller than in adults. Half of them measured less than 10 cm. There were recurrences in 40% of children. The survival rate at 5 years was 49%, 70% if resection was microscopically complete and 7% if not (P < 0.001). CONCLUSIONS: In children, rare adrenal tumors have different diagnostic and prognostic characteristics than in adults; however, recurrences remain frequent. The efficacy of chemotherapy, mainly o,p'-DDD (Mitotane), remains to be evaluated in comparative trials.     

Characterization of the kinetic and mechanistic differences between free-surface and bulk grain growth in WC-Co materials

The rate of grain growth at different high temperatures in the bulk and at the free surface of a WC-Co substrate was measured. The microstructure, phase evolution, and elemental composition at the free surface were characterized at various stages of the grain-growth process and compared to equivalent characteristics of the bulk. A dramatic difference in the rate of grain growth between the free surface and the bulk of the material was observed. Grains in the free surface grew at a much faster rate than those in the bulk. Since this fast rate of growth was found to coincide with the vaporization of the binder phase from the free surface, it is suggested that this increase in the rate of growth is related to a change in the growth mechanism from an interfacial reaction limited growth in the bulk to a surface diffusion rate limited growth at the free surface. The contact points between grains provide bridges for atomic transport from high free-energy regions (small grains) to low free-energy regions (large grains); hence, the contiguity of the material has a strong influence on the rate of growth.